Inflatable kite



June 13, 1961 R. A. POHL INFLATABLE KITE Filed March 5, 1958 IN VEN TOR.

RUSSELL A. POHL ATTORNEY United States Patent 2,988,309 INFLATABLE KITERussell A. Pohl, St. Paul, Minn., assignor to General Mills, Inc., acorporation of Delaware Filed Mar. "3, 1958, Ser. No. 718,821 8 Claims.(Cl. 244-153) The instant invention relates to kites, and morespecifically to inflatable kites of non-rigid construction. Kites may beconstructed of numerous materials which when inflated possess relativerigidity without the employment of added stiffening or support members.Such kites may be transported to a flight site in an uninflatedcondition, filled with air or lifting gas, and sent aloft.

In my. invention the kite is constructed of a thin plastic sheetmaterial sealed to produce an inflatable outer circular portion. Thekite is shaped by inflation which forms the entire structure into anairfoil section which upon exposure to a wind stream has aerodynamiclift and stability.

'It is therefore an object of my invention to provide San inflatablekite having an integral stress beam construction which impartssuflicient strength and rigidity .to its kite to produce aerodynamiccharacteristics without the employment of rigid stiffening or supportmembers.

Another object of my invention is to provide a substantially circularkite formed of a plurality of plastic sheets and provided with aninflatable circumferentially shaped stress beam for providingsubstantial rigidity for the kite.

An object of my invention is to provide a circumferentially shapedinflatable plastic kite having at least two concentric seams within theouter edges of the kite to provide an outer inflatable portion, and aninner membrane section.

Another object of my invention is to provide a circular plastic kitehaving at least two concentric compartments and providing at least oneof said compartments with means therein to admit air thereto.

An object of my invention is to provide an inflatable plastic kitehaving improved flight characteristics by the i provision of an airfoilsurface formed by the inflation of a portion of said kite. 1 Otherobjects and advantages will become apparent in the subsequentspecification and the appended drawings -in which:

. FIGURE 1 is an elevation view of the circular kite; FIG. 2 is aperspective view of the inflated kite of FIG. 1 in flying position;

. FIG. '3 is a sectional view taken along line 3-3 of FIG. 2; FIG. 4 isan elevation view of a modified kite of FIG.

FIG. 5 is an elevation view of a further modification of the kite ofFIG. 1;

FIG. 6 is a sectional view of the kite taken along line together attheir outer edges by a heat seal 16. The tabs 8, 10, and 12 are formedby sheets 4 and 6 and are also sealed along their outer edges. Theinflation tube 14 is sealed only on each side to provide on opening 18for .ef the kite ismaintained.

Patented June 13, 1961 inflating the kite. A seam 20 continuous andconcentric to seam 16 separates the kite into an inflatable portion Band an uninflatable portion A.

Gas admitted through the opening .18 of the inflation tube 14 fillscompartment B causing it to inflate. When compartment B is fullyinflated, the inflation tube 14 is tied or sealed off to retain the gaswithin the kite.

The kite 2 when inflated does not necessarily assume a planarconfiguration but rather assumes a shape with camber and dihedral asseen in FIGS. 2 and 3. It is this camber and dihedral that provides anelfective airfoil for the kite.

Upon inflation the kite deforms into a configuration forming an air foilsection and thereby imparting flight characteristics to the embodiment.By way of further explanation, gas is admitted to the inflation tube 14to inflate compartment B to form a circular stress beam of relativerigidity.

The inflated compartment B exerts radial force through seal 20 oncompartment A. These forces are held in restraint by compartment A andin so doing compartment A becomes taut. The radial forces in compartmentA are relatively uniform circumferentially providing the inflated memberB maintains its circular shape. Since the balance of forces ofcompartments A and B is critical and the entire embodiment is in asemirigid state, the circumferential stress beam B will deform somewhat.elliptically and yield in both directions normal to the plan view. Thisdeformation normal to the plan view is a result of the entire embodimentbeing unable to maintain radial forces in compartment A in a steadystate. Upon deformation of compartment B in a direction normal to theplan view the stress is partially relieved in one direction incompartment A. When the stress is maintained along the theoretical line30, which .is the roll axis of the kite the stress is partially relievednormal to line 30 and the inflated compartment B is deformed as shown inFIG. 2. It can be seen that areas 32 and 34 of compartment B aredeformed normal to the plan view toward the attached bridle. Furthermorethe areas adjacent to the tie tabs 8 and 12 deform in a normal directionto plan view away from. the bridles of attachment. The deformation incompartment B results in the formation of material folds adjacent to tietabs 8, 10, 12 and the inflation tube.

Thus the aerodynamic characteristics are established by inflation whichdeforms compartment B. Improved lift is provided by the camber of thekite. The camber is realized by passing an imaginary straight linethrough tab 10 and inflation tube 14 and the camber will be the bowingaway of the kite from the said imaginary line.

Aerodynamic stability is obtained from the dihedral angle of the kite.This dihedral can be seen in FIG. 2 wherein the fold at tab 10 is thevertex of the dihedral angle D formed by the deformation of compartmentB upwardly from the bridle attachments 8 and .12.

The present kite, inflated to the position shown in FIGS. 2 and 3, couldbe pressurized until it again lies fully inflated within a substantiallyflat plane. However to inflate the kite 2 sufiiciently to effect itsreturn to a normally flat plane requires a higher internal pressure andgreater stresses are created in the material than in the present kitewith loss of flight characteristics.

Considering now the manner in which the kite is to be flown. The kite 2is flown by attaching a bridle 24 to the tabs 8, 10 and 12 and theinflation tube 14. A tail 26 is also secured to the inflation tube 14and may be used to. seal ofi the end thereof when the kite 2 is fullyinflated. By adjusting the angle of attachment of the bridle 24, and bycontrolling the dimensions of the tail 26 stability 'tube 14a.

Asstated previously the kite 2 does not require a high internalpressurization. This allows inflation of the kite in the simple mannerof merely blowing into tube 14 and no bulky inflation equipment isrequired. Additionally the-kite requires no rigid I stiffening membersand-.the resultant deformation by inflation imparts an efficient airfoilto the kite.

-According to conventional wind'lift wing theory the lift created is'due partially to flat plane lift and partially to venturi-effect. Thelift caused by'flat plane theory is the impaction of flight stream airon the front surface of the kite which is inclined at an angle to thewind stream. When flying a kite at an angle to the wind, the wind streamvector direction is broken into two components, 'a vertical and ahorizontal vector. It is the vertical vector which imparts lift to thestructure. 7

The lift caused by venturi action is due to the partial vacuum createdon the upper (back) surface of'the kite due to the higher velocity ofthe air stream over the back surface compared to the velocity of the airstream on the front of the kite.

The camber which is formed by the circumferential stress beamdeformation increases the venturi action thereby increasing the width ofthe kite. Stability is maintained about the roll axis 30 such that whenthe kite tends to roll in one direction the down side of the kite has agreater lift area than the up side lift area in relation to the windstream therefore causing counter rotation about the roll axis to returnthe kite to normal position.

The deformation of the inflated circumferential stress 'beam to impartdihedral to the air foil improves the stability by reducing the up sidelift area and increasing the down side lift area during a roll.

Referring now to FIG. 4. The kite 30 is somewhat identical inconstruction to the previous embodiment except for a plurality ofperforations indicated by the numeral 32. These perforations provide airspillout when 1 the kite 30 is flown during adverse wind conditions andassist in maintaining the stability of the kite. For example, while theprevious embodiment canbe flown during wind conditions of from 6 mph. to8 mph, the present embodiment can be flown during fluctuating windconditions of up to 12 mph. since greater air spillout is provided.

In addition to the above embodiments the kite may be constructed asshown in FIGS. 5 and 6, wherein inflatable compartments A and B areprovided.

Referring first toFIG. 5, the kite 32a is substantially the same as inthe previous embodiments except that the total area of the kite isinflated. For example, seams 16a and 18a divide the sheets 4a and 6ainto two compartments A and B which are inflatable through the inflationThe only difference in the seams 16a and 18a and those of the kite 2 ofFIG. 1 is that an opening 17a is provided in seam 16a adjacent theinflation tube 14a. Thus both compartments are inflated from a singleopening. As will be noted from the drawing, tabs 8a, 10a, and 12a arealso provided on the kite 32a and facilitate attachment of a bridle tothe kite.

.Referring now to FIG. 6, the kite 30a when inflated assumes generallythe configuration of the kite 2 of FIG. 3. It will be noted, however,that compartment A, when inflated, extends slightly forward at 6asomewhat more than the previous embodiment. While this slightly reducesthe efficiency of the airfoil, greater over-all strength is afiorded tothe kite 3001 by this inflation.

As stated earlier the general line of tensioning which occurs in thecentral compartment of the kite of my invention does not always occur inthe relationship indicated by the line 35 of FIG. 1. For example, theline of tensioning may occur in an angular relationship relative to theinflationtube. Therefore in the previous embod'iments it would benecessary, in some instances, to manually bias the deformation in" thedesired direction in order to achieve the configuration shown. Howeverin the ensuing embodiment I provide a means which will positively assurethe desired configuration of the kite.

Referring now to FIG. 7 the kite 40 of FIG. 7 is constructed of plasticsheets 42 and 44 which are seamed together to form a'circular kitesubstantially identical to the previous embodiment. The kite 40' alsohas integral therewith tabs 46, '48, and 50 and an inflation tube'52.Circular seams 54'and 5'6 secure the sheets 42 and 44 together to formcompartments C and D and a radial slot 43 is provided in compartment 0to allow for adequate "air spillout when the kite '42 is flown. As willbe noted from FIGS. 7 and 8 the sheet 42 is only a partial sheet beinggenerally of a doughnut shape suflicient to form the circularcompartment D. By constructing sheet 42 in this manner a resultantsavings in material is achieved and a much lighter kite is produced.

Looking now at the outer seam 56. The seam 56 secures the sheets 42 and44 together along their outer peripheral edges and is provided withconcave seams or indentations 58 adjacent the tabs 46, 48, and 50. Theseindentations perform an essential function in the: present embodimentfor as pressure is admitted to compartment D they tend to effect thebending of the material of sheet 42 along the dotted lines 60 to controlthe configuration of the kite 40. By positioning a third concaveindentation adjacent tab 48 as shown a third bending occurs on the rearsurface of the kite and a shouldered effect is created generally alongline 60 adjacent the tab 48.

Thus I have in the drawings and specification presented a detaileddisclosure of my invention; while I have described particularembodiments it is to be understoodthat modifications and changes willoccur to those skilled in the art, and therefore I intend to be limitedonly by the scope of the appended claims.

Now, therefore, I claim:

1. In an inflatable kite, two normally flat circular similar sections offlexible plastic sheet material, each such sheet having the same area, afirst airtight seam securing the sheets together along theirouter-matching edges, a second airtight seam securing said sheetstogether concentric of said first seam providing an inflatable portionbetween said seams and an uninflated portion in the center of said kite,an inflation tube integral with said sheets for admitting a fluid tosaid inflatable portion, whereby admission of the fluid to saidinflatable portion produces an air foil having both dihedral and camber.

2. In an inflatable kite, a plurality of normallyflat circular sectionsof flexible plastic sheet material of equal size including tab portionssecured together at their outer edges by a first airtight seam extendingaround the outer edges of said sheets, a second airtight circular seamspaced from said first seam concentric therein .dividing the kite intoan inflatable portion and an uninflatable portion, an inflation tubeintegral with said inflatable portion for inflating said inflatableportion, whereby inflation of said inflatable portion produces adihedral and a'camber in the inflatable portion and tensions in saiduninflatable portion.

3. In a circular inflatable kite, a' first sheet of normally flatcircular flexible plastic material, a second normally flat circularflexible plastic sheet alignable circumferentially with said first sheetand provided with a circular opening concentric of said sheets, theoutside diameter of said second sheet being the same as the diameter ofsaid first sheet, a first airtight seam securing said sheetstogether attheir outer circumference, a second air tight seam securing the inneredge of said second sheet to said first sheet to provide a circularinflatable portion anda singlesheet uninflatable portion, and aninflation tube integral with said circular inflatable portionfor'in'flating said inflatable portion with a gas, whereby inflation ofsaid inflatable portion produces an air foil on saidkite having'acompound curvature.

provided at the outer matching edges of said first and second sheets,one of said tabs being located at the front of the longitudinal axis ofsaid kite, the other two said tabs located on the transverse axis ofsaid kite, said transverse axis tabs being partly defined by said firstseam to provide a seamed surface inward of said outer matching edges tofacilitate forming a camber when said inflatable portion is inflated.

5. The combination of claim 4 including an attachable tail means forclosing of said inflation tube for maintaining inflation of saidinflatable portion.

6. An inflatable kite constructed of a plurality of substantiallycircular normally flat flexible plastic sheets of equal size, a firstair tight circular seam securing the sheets together along their outercircumferential edges, a second air tight circular seam spaced interiorof said first seam and concentric therewith forming a stress beamcompartment, an inflation tube integral with said stress beamcompartment for inflating said stress beam compartment, the relativediameters and locations of said first and second seams insuringinflation of said stress beam to a curved shape and providing for saidkite having an aerodynamic shape with both camber and dihedral.

7. An inflatable circular kite constructed of similar circular sectionsof normally flat flexible plastic sheet material, a first air tightcircular seam securing the sheets together along their outer matchingedges, a second air tight circular seam within said first seamconcentric therewith dividing the kite into a first inflatablecompartment and a second uninflated compartment, an inflation tubeintegral with said sheets for inflating said first compartment and aplurality of perforations in said second Compartment adapted to provideair spillout when said kite is flown, the relative diameters andlocations of said first and second seams insuring inflation of saidinflatable compartment to a curved shape and providing both camher anddihedral in said kite.

8. An inflatable circular kite constructed of similar circular sectionsof normally flat flexible plastic sheet material of equal size, aplurality of tabs integral with said sheets and spaced apart around thecircumference thereof, a first air tight circular seam securing thesheets together at their outer matching edges, a second air tightcircular seam within said first seam concentric therewith dividing thekite into two compartments, a concave seam adjacent each of said tabsextending inwardly toward said second seam, and an inflation tubeintegral with said sheet material for inflating said kite, the relativediameters and locations of said first and second seams insuringinflation of said kite to aerodynamic shape having both camber anddihedral.

References Cited in the file of this patent UNITED STATES PATENTS1,328,848 Ramauge Jan. 27, 1920 1,529,076 Marchessault Mar. 10, 19251,572,187 Cooper Feb. 9, 1926 1,929,005 Rolkerr Oct. 3, 1933 2,486,158Haas Oct. 25, 1949 2,733,880 Burrell et a1 Feb. 7, 1956 2,743,510 Mauneyet a1 May 1, 1956 2,769,605 Sparkman Nov. 6, 1956 2,824,589 Neisler etal Feb. 25, 1958 FOREIGN PATENTS 215,241 Germany Oct. 23, 1909

